【作者】 关文娟；

【导师】 高从堦； 张贵清；

【作者基本信息】 中南大学 ， 冶金工程， 2013， 博士

【摘要】 摘要：现有钨钼分离工艺处理高钼含钨溶液存在W损大、除Mo不彻底、成本高和对环境污染严重等不足。本文针对此提出了一条从高钼含钨溶液中分离钨钼的清洁高效新工艺,即双氧水配合—TRPO/TBP混合萃取剂萃取分离钨钼新工艺,并成功完成了工业化试验。本研究针对钨酸铵溶液调酸制备双氧水配合溶液存在的困难,创新性的提出蒸发脱氨配合法和双极膜电渗析(BMED)配合法由高钼钨酸铵溶液制备用于双氧水配合萃取分离钨钼的萃取料液,大量减少了调酸过程无机酸的消耗,具有清洁环保的优点；首次采用TRPO/TBP混合萃取体系从高钼钨酸铵溶液中分离钨钼,能协同萃取Mo,反协同萃取W,从而实现了降低W损、提高除Mo率的目的。新工艺克服了传统钨钼分离工艺的不足,从高钼含钨溶液中萃取分离钨钼,具有除Mo彻底、W收率高、Mo产品附加值高、成本低、和清洁环保等一系列优势。本研究的主要内容包括萃取料液的制备、萃取-反萃取单级试验、多级模拟萃取试验、连续运转试验、工业化试验和TRPO/TBP混合体系对W和Mo的协萃效应及机理探讨。萃取料液制备试验考察了H2O2用量、pH值、温度等因素的影响。蒸发脱氨配合法试验结果表明：蒸发脱氨调酸能比直接加酸调pH减少90%以上的耗酸量,配合转化过程控制H2O2用量为k=1.9(k是H2O2摩尔数与w和Mo摩尔总数的比值),温度45℃,初始pH值1.90,时间60min,W和Mo的H2O2配合转化率高于95%,H2O2分解率低于15%。BMED配合法试验结果表明：BMED过程中控制盐室溶液pH值3.20-3.50,运行210min,其电流效率高于72%,直流电耗(以NH4+计)低于0.088kW·h·mol-1;配合转化过程中H2O2无分解,W、Mo配合转化率和H2O2利用率均接近100%。两种方法均可制得合格的萃取料液。采用TRPO/TBP煤油体系从萃取料液中萃取分离钨钼,用分液漏斗进行单级条件试验,考察TRPO和TBP浓度、接触时间、温度、H2O2用量和pH值等因素对萃取过程的影响。试验结果表明：TBP的加入不仅能改善萃取和反萃取的分相性能,而且能提高萃Mo率,抑制W的萃取,从而提高Mo/W分离性能。最佳萃取条件为：H2O2用量k=1.2-1.5,萃取料液放置时间24-48h,萃取水相初始pH值1.5-2.0,萃取相比O/A=1/1,接触时间5min,温度15-25℃；用组成为2%(V/V)TRPO+80%(V/V) TBP+18%(V/V)磺化煤油的有机相在优化条件下对含WO390-120g/L, MO/WO3质量比10-15%的萃取料液进行萃取,Mo的单级萃取率大于63%,W的萃取率小于2%,分离系数βMo/W大于80。反萃取过程中W和Mo得到了二次分离,NH4HCO3溶液具有分相性能好,反Mo率高,Mo/W选择性好等优点,是最合适的反萃体系。最佳反萃取条件为：反萃剂1.0-1.2mol/L NH4HCO3,相比O/A=8/1-10/1,接触时间10min,温度15-25℃。此条件下对负Mo9.90g/L, WO32.08g/L的有机相进行反萃,Mo的单级反萃率高于95%,w的单级反萃率低于15%,反萃液中Mo浓度可达70-90g/L。用分液漏斗模拟多级错流萃取和逆流萃取。绘制了不同条件下的萃取等温线。运用Kremser方程计算与分析了萃取平衡pH与逆流萃取级数、萃余液中Mo、W浓度之间的关系。在此基础上,通过中间1级调酸方法改变了萃取平衡pH值的分布；通过2段式逆流萃取充分利用了放置时间对除Mo深度的有利影响,从而达到了提高除Mo率,保证低W损,进一步优化Mo、W分离指标的目的。用混合澄清槽进行了BMED配合法—双氧水配合萃取分离钨钼的连续运转扩大化试验,其中的2段式12级逆流萃取-2段式反萃取连续运转试验条件为：有机相组成为3%(V/V)TRPO+42%(V/V)TBP+55%(V/V)磺化煤油,萃取料液中H2O2用量为k=1.5,放置时间48h；1段萃取为8级逆流,萃取水相初始pH为2.00-2.05,1-3级为调酸级,调酸级平衡pH为0.96-1.20,有机相操作容量7.57-8.97g/L Mo;2段萃取为4级逆流,1段萃余液放置36h后作为2段萃取的料液,萃取水相初始pH为1.00-1.05,有机相操作容量0.12-0.26g/L Mo;1段反萃取和2段反萃取均为3级并流,2段反萃剂为0.05mol/L NH4HCO3,得到的2段反萃液补入0.8mol/L NH4HCO3作为1段反萃剂,反萃取流比为O/A=6/1。在此条件下得到的2段萃余液含WO3102-123g/L, Mo0.0060-0.017g/L, Mo/WO3质量比小于1×10-4。取2段萃余液加NH3·H2O后进行蒸发结晶,得到的APT产品满足国标GB/T10116-2007中对0级APT产品杂质含量的要求。对TRPO/TBP混合体系萃取Mo和W的基础理论进行了研究探讨。大量试验数据和红外光谱分析结果表明：TRPO/TBP煤油体系对Mo表现出协同萃取效应,对W表现出反协同萃取效应,试验条件下的协萃系数分别为RMo,协=1.31-2.81和RW,协=0.21-0.53。TRPO能萃取未和H2O2配合的三氧化钨水合物,形成第三相,萃取反应为中性配合机理。TBP的加入能消弱TRPO中P=O键对W6+的萃取能力,从而抑制W的萃取,消除第三相,提高Mo/W分离性能。建立了一条年产50tAPT的工业化试验生产线,连续运行21个月状况良好。成本分析结果表明：对MO/WO3质量比为12.5%的高钼钨酸铵溶液而言,采用双氧水配合萃取法较选择性沉淀法能节省除Mo成本5746元/tWO3。新工艺与现有钨钼分离工艺相比,在处理Mo/WO3质量比>5%的钨钼混合溶液时,具有除Mo彻底、W收率高、Mo产品附加值高、成本低、和清洁环保等一系列优势。图80幅,表57个,参考文献175篇。更多还原

【Abstract】 Abstract:The current processes for separating Mo and W from tungstate solution with high ratio of Mo/W (molybdenum/tugsten) have shortages such as high co-precipitation loss of W, incomplete removing of Mo, high cost and seriously environment pollution. Aiming at this situation, a novel cleaning efficient process for separating Mo and W from tungstate solution with high ratio of Mo/W, i.e. process of extraction separation of Mo and W by hydrogen peroxide (H2O2)-complexation with a mixture extractant tri-alkyl phosphine oxide (TRPO) and tributyl phosphate (TBP) was developed and the industrial test was carried out in this paper.Aiming at the difficulties presented in the acid regulation of the preparation of the H2O2-complexation solution from the ammonium tungstate solution, two methods, the evaporation deamination complex method and the dipolar membrane electrodialysis (BMED) complex method, on preparation of feed solution for extraction from the ammonium tungstate solution containing high Mo were proposed. The new methods were clean and environmental friendliness, and by which the consumption of mineral acid was largely decreased. The mixture extractant TRPO and TBP was used for separating Mo and W from the ammonium tungstate solution containing high Mo for first time. There was a synergistic extraction effect of Mo with TRPO/TBP and an antagonistic extraction effect of W with TRPO/TBP. Thus, the purpose of the increase of the removing of Mo and to decrease the extraction of W was carried out. In comparision to the traditional process for separating Mo and W, the new process provided obvious advantages including deep Mo removing, high recovery of W, high added value of Mo product, low cost, clean and environmental friendliness.The main research contents included the preparation of feed solution for solvent extraction separation of Mo and W by H2O2-complexation, single-stage extraction and stripping test, multi-stage extraction test, continuous running test, industrial test and fundamental theory research on extraction.The effects of H2O2dosage, pH value and temperature were investigated in the test of preparation of feed solution for extraction. The results indicated that the evaporation deamination complex method reduced the acid consumption by more than90%in comparison to the traditional directly acid regulation complex method. The H2O2-complex transformation rates of W and Mo were higher than95%and the decomposition rate of H2O2was less than15%at a H2O2dosage of k=1.9(k is the mole ratio of H2O2to W and Mo), temperature45℃, initial pH1.90for60min in the H2O2-complexation transformation process. The results of BMED complex method indicated that the current efficiency was higher than72%and the direct current consumption (byNH4+) was less than0.088kW·h·mol-1at a pH of salt compartment solution of3.20-3.50and with running time210min in the electrodialysis process. There was no H2O2decomposed, and the transformation rates of W, Mo and utilization rate of H2O2were close to100%in the H2O2-complex transformation process. The qualified feed solution for extraction could be prepared by both the two methods.The single-stage extraction test of solvent extraction separation of Mo and W from feed solution was carried out using separating funnel with tri-alkyl phosphine oxide (TRPO)-tributyl phosphate (TBP)-kerosene system. The effects of concentra-tion of TRPO and TBP, contact time, temperature, H2O2dosage and pH value on the extraction were investigated. The results indicated that the addition of TBP in organic not only improved phase separation both in extraction and stripping, but also increased the extraction of Mo and decreased the extraction of tungsten (W), and hence improved the separation properties of Mo/W. The optimum extraction conditions were as followed:H2O2dosage k=1.2-1.5, storing time of feed solution24-48h, initial pH value of aqueous solution1.5-2.0, O/A phase ratio1:1, contact time5min, temperature15-25℃. Under the optimum conditions, the extraction of Mo was higher than63%and the separation coefficient βMo/w was larger than80using aqueous solutions containing90-120g/L WO3and Mo/WO3mass ratio of10-15%with a mixture of2%(V/V) TRPO and80%(V/V) TBP in kerosene.The further separation of W and Mo was realized in stripping process. NH4HCO3was the optimum stripping agent since its good phase separation, effective stripping of Mo and high Mo/W selectivity. The optimum stripping conditions were as followed:NH4HCO310-1.2mol/L O/A ratio8:1-10:1, contact time10min and temperature15-25℃. Under the optimum conditions, the stripping of Mo was higher than95%in comparison that of W less than15%after one contact with the organic loaded9.90g/L Mo and2.08g/L WO3, and the concentration of Mo in strip liquor was70-90g/LThe muti-stage cross-flow and countercurrent extraction were been simulated using separating funnel. The extraction isotherms for Mo were plotted under different conditions. The relationship between the stage of countercurrent extraction, concentrations of Mo and W in raffinate and the equilibrium pH value was calculated and analyzed by kremser equation. On this basis, the method of acid regulation in one of the middle stages was proposed and the distribution of equilibrium pH value in each stage of extraction was changed. The process of2-section countercurrent extraction was proposed and the positive effect of storing time on the deep removing of Mo was fully utilized. Thus, the purpose for the separation indexes optimization to increase the extraction of Mo and to decrease the extraction of W was carried out.The continuous running test of the BMED-solvent extraction separation of Mo and W by H202-complexation was carried out using mixer-settler. The conditions of the2-section12-stage countercurrent extraction and2-section stripping test were as followed:the organic phase was comprised of3%(V/V) TRPO and42%(V/V) TBP in55%(V/V) kerosene, the H2O2dosage and the storing time of the feed solution for extraction was k=1.5and48h respectively. In the first-section extraction there was8-stage countercurrent extraction and the1-3stage was the acid regulation stage, the initial pH of aqueous solution was2.00-2.05, the equilibrium pH of the1-3stage was0.96-1.20, the operation capacity of organic phase was7.57-8.97g/L Mo. In the second-section extraction there was4-stage countercurrent extraction, the feed solution of the second-section extraction was the raffinate of the first-section stage with storing time36h, and the initial pH value was1.00-1.05, the operation capacity of organic phase was0.12-0.26g/L Mo. In the first and the second section stripping, there were both4-stage cocurrent extraction, the stripping agent in the second-section stripping was0.05mol/L NH4HCO3, the stripping agent in the first-section stripping was the strip liquor of the second-section stripping with0.8mol/L NH4HCO3addition, both the O/A ratio in the two sections stripping were6:1. Under the conditions, the raffinate of the second-section extraction was containing102-123g/L WO3,0.0060-0.017g/L Mo, and in which the Mo/WO3mass ratio was less than1×10-4. The APT product was obtained by evaporation deamination from the raffinate of the second-section extraction with NH3·H2O addition. The product could meet the requirement of0grade of APT of the national standards GB/T10116-2007of China.The fundamental theory of extraction of Mo and W with the mixture extractant TRPO/TBP was researched. It was confirmed by a lot of experimental results and infrared (IR) analysis that there was a synergistic effect between TRPO/TBP and Mo, and a antagonistic effect between TRPO/TBP and W. Under the experimental condition, the synergistic coefficient of Mo and W was RMo,协=1.31-2.81and Rw,协=0.21-0.53respectively. The tungsten trioxide (WO3) hydrate without H2O2-complexation could be extracted by TRPO and formed a third phase. The extraction reaction was neutral complex mechanism. The coordination ability of the P=O bond in TRPO for W6+was weakened by the addition of TBP. Thus, the extraction of W was restrained, the third phase was eliminated and the separation properties of Mo/W were improved by the addition of TBP into TRPO.An industrial test production line for produce50tAPT per year was established in the factory. It had successfully and continuously running for about21month. The cost analysis indicated that, to the ammonium tungstate solution containing high Mo with Mo/WO3mass ratio of12.5%, the novel process for separating Mo and W by H2O2-complexation could save the cost of removing Mo of4472yuan per WO3in comparison to the selectively precipitation method. Compared with current process for separating Mo and W, the new process provided obvious advantages including deep Mo removing, high recovery of W, high added value of Mo product, low cost, clean and environmental friendliness, especially when the MO/WO3mass ration in the mixture solution was higher than5%.更多还原